Sports are played on turf fields having markings that delineate the playing field or for other purposes. The fields have evolved from natural turf surfaces to manufactured, synthetic, or artificial turf surfaces.
When a turf playing field is used for multiple purposes, i.e., for different sports or activities requiring different markings, the old markings must be removed and newer ones applied usually under severe time constraints.
Turf playing fields have traditionally been marked with different types of opaque materials, including stones, and chalk. On modern playing fields, the lines and markings are primarily painted, woven, glued, or sewn directly into the natural or artificial playing turf surface. With the exception of chalk, these methods are considered substantially permanent marking technologies because only through severe methods can the markings be removed from the turf in a satisfactory manner.
Permanent marking technologies offer a number of advantages, such as opacity, integrity, and permanence. Opacity means the marking can be visually differentiated from the turf. Integrity means the marking stays in place even upon contact. Permanence keeps the marking in place during the intended use and in the most severe weather.
Other than woven, glued or sewn-in markings, solvent-based paints are the next most permanent marking technology. The advantages of solvent-based paints are superior durability due to excellent adhesion to artificial and natural turf, and excellent early resistance to water because of fast dry times.
Disadvantages of solvent-based paints include flammability, air pollution in terms of high VOC (volatile organic compound) emissions, toxicity, and possible damage to the artificial or natural turf and its various subsurface components. Cleanup of the application equipment after installation requires a solvent. Also, mistakes in marking are difficult to repair once applied. Furthermore, removal of solvent-based paints is a difficult and labor-intensive process, resulting in damage to the turf because of the high amounts of solvent and mechanical abrasion that are used. Removal of solvent-based paints often involves spraying copious quantities of flammable solvent on the paint, and then physically wiping it up with an absorbent material.
Water-based paints are also considered a permanent marking technology. Water-based paints are non-flammable, have little to no VOCs, are non-toxic, and are chemically benign to the turf surface. Water-based paints and equipment can be cleaned up with soap and water while still wet, and are very easy to mix and apply.
Disadvantages of water-based paints include slow dry times, reduced early water resistance as compared with solvent-based paints (may be washed off with rain or fog before the film is formed), and mistakes are also difficult to repair. Removal of water-based paints, once dried, is also very difficult, resulting in damage to the turf playing surface because of the use of solvents and mechanical abrasion.
Water-based and solvent-based paints are permanent enough that the removal process is not effective at removing all the paint and leaves paint adhering to the turf, which is referred to as “ghosting.” Residual removal requires mechanical brushing. In reality, the only way that water-based and solvent-based paints are removed is through mechanical means like physically scraping the paint film from the turf.
Latex-type paint, also a water-based paint, must be broken down with high-pressure sprays, aggressive brush systems, steam cleaners, and different types of chemical detergents. Because of the high pigment to binder ratio in latex-type paints, the overall adhesion of this type of paint is unreliable and tends to wear off easily, while at the same time leaving shadowing or trace amounts of paint adhered to the turf that is difficult to fully remove. Power brushes and other abrasive systems cause damage to the turf as well as damage to the subsurface infill beneath the turf. Brushes and abrasive systems can leave holes in the turf. These harsh removal processes can drive some of the solids into the turf infill, leaving the broken paint chips in the turf field that may resurface at a later date. Rain, walking, or driving on the turf field can cause these chips to migrate to the surface, producing undesirable spots and markings on the turf field.
To remove a latex-type paint, harsh chemical solvents are required, sometimes requiring wax or other substances to keep the chemicals on the surface during dissolution. The resulting compound is a gelatinous mixture of paint and resins that are difficult to separate from the turf.
The advantage of water-based and solvent-based paint is that they are highly durable because they are made with permanent, water insoluble resin systems. The disadvantage comes from the fact that they cannot be easily removed. Consequently, the cost of the materials and the time and labor involved to remove these paints, as well as their impact on the turf, makes it impractical to use them when multi-use field configurations are required. Accordingly, there is a need for a turf marking composition that is water insoluble once dried, but that can be readily removed. The present invention provides this and related advantages.